ARM: dts: at91: tse850: the emac<->phy interface is rmii

This went unnoticed until commit 7897b071 ("net: macb: convert
to phylink") which tickled the problem. The sama5d3 emac has never
been capable of rgmii, and it all just happened to work before that
commit.

Fixes: 21dd0ece ("ARM: dts: at91: add devicetree for the Axentia TSE-850")
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/ea781f5e-422f-6cbf-3cf4-d5a7bac9392d@axentia.se

arch/arm/boot/dts/at91-tse850-3.dts

@@ -262,7 +262,7 @@ &pwm0 {
 &macb1 {
 	status = "okay";
 
-	phy-mode = "rgmii";
+	phy-mode = "rmii";
 
 	#address-cells = <1>;
 	#size-cells = <0>;